Application of the membrane filter technique to bromodeoxyuridine immunochemistry for exfoliative cytology

The membrane filter technique for smear specimens of tumors in bromodeoxyur idine (BrdU) immunochemistry is described. The staining results of Raji cel ls processed using the filter technique was compared with that obtained by the conventional cytospin method. Although the BrdU mean labeling index (LI ) for in cytospin specimens was almost the same as the LI in membrane filte r specimens, filter specimens showed excellent staining and less cell destr uction compared with those processed by cytospin. Small amounts of tumor sp ecimens such as squamous cell carcinoma and polymorphous low-grade adenocar cinoma also were processed using the membrane filter appliance, For squamou s cell carcinoma, the LI for the filter specimens was 5.36 +/- 0.38 and tha t of the paraffin sections was 5.56 +/- 0.38. The membrane filter technique provided relatively undamaged specimens for exfoliative cytology and will be useful for immunohistochemical evaluation of tumor cells and for routine , noninvasive cytological screening.